The present invention is directed generally to a valve mechanism and, in particular, to a valve mechanism specifically designed to allow use of a lower force to actuate the valve while providing superior sealing characteristics.
A valve mechanism of the general type under consideration is described for example, in German Patent Publication No. DE 27 57 803 (corresponding to British Published Patent Specification No. 1, 556, 942). Such a valve mechanism includes a valve seat, a valve closure member and an actuating element which drives the valve closure member. The armature of an electromagnet in the valve is the actuating element. The valve closure member is disposed on the armature in such a way that it can move relative to the armature, toward or away from the armature. A spring is disposed between the armature and the valve closure member. By passing current through the electromagnet, the armature together with the valve closure member can be moved from a first position, such as the open position of the valve, to a second position, such as the closed position of the valve.
A valve mechanism of this construction generally has only a relatively small flow cross section, or in other words a relatively small nominal width, in order to minimize the actuating force for the valve. A large flow cross section would require a relatively large actuating force and thus the use of powerful electromagnets, which in turn are relatively large in size.
Accordingly, it is desired to provide an improved valve mechanism of the type under discussion which allows a lower actuating force to be used even when a larger flow cross section is provided.
Generally speaking, in accordance with the present invention, a valve mechanism including a valve housing, is provided. The valve housing includes a pressurized fluid inlet and a pressurized fluid outlet. A movable valve member defining a longitudinal axis is positioned on the valve housing for movement between a first position where the valve is opened and a second position where the valve is closed. The valve member includes a valve closure member having a predetermined configuration disposed thereon for movement in the direction of the longitudinal axis. A damping element is disposed between the valve member and the valve closure member. The valve housing has a valve seat defining an opening through which pressurized fluid flows when the valve is opened. The damping element cushions the impact of the valve closure member against the valve seat when the valve member is closed. The valve seat and valve closure member define a sealing width which corresponds essentially to the diameter of the opening. At least a portion of the valve closure member is made of a hard material. The predetermined configuration of the valve closure member allows it to have essentially only line contact with valve seat when the valve is closed.
The present invention offers in particular the advantage that the valve mechanism can work with relatively low actuating energy even if it has relatively large nominal width. As used herein, the nominal width corresponds approximately to the sealing width of the valve. For the present purposes, nominal width is understood as the bore diameter of the valve seat, while the sealing width is understood as the largest diameter of the valve seat with which the valve seat is still in contact with the valve closure member when the valve is closed. In the valve mechanism of the present invention, the largest diameter of the valve seat corresponds approximately to the bore diameter of the valve seat, and so the valve seat has essentially only peripheral or line contact with the valve closure member.
The sealing width of a valve is critical to its sealing force. If the valve has large sealing width and thus a large sealing force, a relatively large restoring force, such as exerted by a relatively strong spring, is necessary to return the valve to its open position from its closed position after a closing process. Accordingly, a relatively large actuating force, sufficient to overcome the restoring force, is necessary to close the valve. On the other hand, if the valve has a sealing width corresponding approximately to its nominal width, as is the case in the valve mechanism of the present invention, the restoring force necessary to open the valve is relatively small. The actuating force necessary to overcome the restoring force during the process of closing of the valve is then also relatively small. The inventive valve mechanism can therefore have a relatively large nominal width, thus achieving the advantage of short air-admission and venting times for pneumatic devices connected to the valve mechanism.
If an electromagnetic arrangement is used for actuating the valve mechanism, it can also be kept relatively small by virtue of the relatively small force necessary for actuating the valve, thus achieving a reduction of weight and cost in addition to the advantage of a smaller space requirement.
Due to the fact that the valve closure member of the present invention may have a conical or spherical shape and may be made of relatively hard material, and the fact that the valve seat may be formed by the circumferential edge of a flow orifice, essentially only peripheral edge contact between the valve seat and valve closure member is achieved while the valve is closed.
In addition, by disposing a damping element between the valve closure member and actuating element, the impact energy is absorbed and thus wear of the valve closure member is reduced. The consequence of wear or plastic deformation caused by undamped impact would be enlargement of the area of contact between the valve closure member and the valve seat. In turn, the sealing width of the valve would become undesirably large and large leaks would develop due to wear.
Accordingly, it is an object of the present invention to provide an improved valve mechanism used to control the flow of pressurized fluid.
Another object of the present invention is to provide a valve mechanism in which a smaller actuating force is required to actuate the valve.
A further object of the present invention is to provide a valve mechanism in which a larger flow cross section can be presented without a corresponding increase in the actuating force.
A still further object of the present invention is to provide a valve mechanism of the type described, in which larger nominal widths can be achieved while largely avoiding the noted disadvantages of the prior art.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.